Digital data transmission systems, such as, digital subscriber line (DSL) systems, have quickly emerged as a high quality solution for high speed Internet access and other services associated with high speed Internet services, such as, voice over Internet protocol (VoIP) and streaming video services. These systems can provide for multiple physical layer bearers. Separate bearers can be used to provide distinct data transmission characteristics that may be needed for different types of data and different applications. For example, voice data may require low latency, while video data may require a low error rate. Error control coding and interleaving of bearer channels generally result in a trade-off between latency and error rate.
Typically, each bearer is a distinct channel that can convey a portion of the total data payload to be transmitted over a communication line. Bearers can be implemented by assigning a certain subset of the total payload data bits in each physical layer frame. Further, the bit rate for each bearer is determined by a parameter stored in a data object for use with a simple network management protocol-management information base (SNMP-MIB). MIB objects can be controlled via GET and SET messages from an element management system (EMS). The bit rate for each bearer is typically set when a particular service is provisioned. The bit rate may change in response to changes in the transmission quality or changes to the service characteristics.
The bit rate for a particular bearer may need to change is response to beginning or ending a session for an application. For example, the bit rate may need to be changed in response to changing a number of simultaneous video programs that are being transmitted on a line. Additionally, an application may need to dynamically change a bit rate for a bearer. For example, a video program may need to change a bit rate as the content changes between standard definition video and high definition video. As a result, the bit rate for a bearer may need to change within a fraction of a second. However, the standard element management systems typically perform operations with a delay of ten to thirty seconds.
Also, it is inefficient to set a bit rate for a bearer at a high level for a long period of time since other bearer's within the same line could make use of the additional capacity. As such, the bearer bit rate should ideally increase almost instantly when necessary and decrease when the added capacity for the bearer is not needed.
Accordingly, there is a need for an improved system and method of managing data bit rates for digital data transmission.